Exposure to mixed metals/metalloids in early childhood: a cross-sectional cohort study in children from Sevilla, Southern Spain

The synergy of exposure to neurotoxic substances, including some metals and metalloids has emerged as a global concern due to its effects on neurodevelopment. Thus, this study determined the presence of Al, Cr, Mn, Ni, Cu, Zn, As, Se, Cd, and Pb in hair and their relationship with the developmental profile in a cohort of 254 children at 6, 12, 18, and 24 months of age in Seville, Southern Spain. A cross-sectional examination was conducted, including the measurement of metal-metalloid levels in hair using mass spectrometric analysis with inductively coupled plasma (ICP-MS). The children's developmental profile was assessed using the Battelle Developmental Inventory (BDI). The results showed that each hair sample contained 2 to 10 metals or metalloids. A multiple regression analysis found that a model including all elements-along with factors such as age, number and levels of detected metals/metalloids, maternal education, and developmental measures-was significantly associated with overall development (BDI score) as well as the personal-social, cognitive, and language domains. In this sense, Pb, Al, Mn and As were demonstrated to be the elements with more negative correlations to the different parameters. The interaction effects of metal-metalloid mixtures reinforce global concerns about their differentiated impacts on early childhood, depending on sex and the affected developmental domain. These findings are alarming due to their potential implications as predictors of developmental deficits, psychomotor skills, and future school performance. Thus, environmental surveillance and infant biomonitoring in non-industrial urban settings, such as Seville, highlight the need to redefine territorial strategies for reducing everyday environmental pollutants. This study underscores the importance of addressing invisible chronic exposures and identifying social determinants that modulate neurotoxicity and neurodevelopmental disorders.